Congestion control mechanisms in Internet transport layers, such as Transmission Control Protocol (TCP) congestion control mechanisms and Stream Control Transmission Protocol (SCTP) congestion control mechanisms, have been designed to assume that packet losses are an indication of network congestion in the path. Additional mechanisms have been developed to provide congestion indications, e.g. explicit congestion notification (ECN), but these mechanisms are not consistently supported. Accordingly, transport layer congestion control mechanism implementations must still treat any packet loss as an indication of congestion.
Congestion control mechanisms adjust for congestion by resizing the congestion window (cwnd) size for the transmission. Even for layer-4 TCP and SCTP congestion signaling, such as ECN Congestion Experienced (CE) signaling, congestion control mechanisms react to the signaling in the same manner in which they react to actual lost packets.
As network technology evolves to include wireless networks, networks have begun to see random packet losses. For example, third generation (3G) wireless networks can see 1% packet loss rates even under perfect environmental conditions. Similarly, Long-Term Evolution (LTE) wireless users may see 10−4 or 10−6 percent packet loss rates even under the best of conditions. As wireless devices move around, they can experience significantly higher random packet loss rates due to the physical location of the device, and irrespective of current network congestion.